I think best way for governments is to make it legal buying and selling old beads.if the arachelogists problem is loosing their chances of study about those beads.they can make a law for every one owns an ancient bead to show and present their find to study and then let it to be sell.it is better or just make it illegal and send beads to museums wear house for decades and what happens to them in that time .no one knows.
I never offend arachelogists and I like their job but who can guarantee all the staff they find in digging goes to museum.
I always advice people to not dig graves.but beads just not come from graves.many time after heavy rain they go out of earth. Like what happened in jeroft sout east iran.
finally I believe dig a grave is not good but if someone found open destroyed graves with beads or on the farm .mountain or else.thst person should be able to be owner of that and sell it.
The point is studying that bead by arachelogists can give historical information but not a reason to say having old beads is illegal.
Many times I have seen BC beads on an old nomad lady.and I ask where did you find it .respond is my mother has been having this before me.
Or I see their tent has been near ancient sites and generation to generation they found beads without destroying any grave.
Ali